I. Technical Field
The present invention relates to a composite sensor equipped with a vibration-type angular velocity sensor element and an acceleration sensor element.
II. Description of the Related Art
For a composite sensor of this type, a structure having an exterior package in which a vibration-type angular velocity sensor formed by packaging therein a vibration-type angular velocity sensor element and a signal processing circuit such as an IC are disposed, and an acceleration sensor formed by packaging therein an acceleration sensor element and a signal processing circuit thereof are known. As prior art reference information relating to the present application see, for example, JP-A-2003-4450.
There has been an increasing need for a composite sensor to further reduce the size, as a system incorporating such composite sensors becomes more compact and expands in functionality. A possible structure to meet this need is to integrally package the vibration-type angular velocity sensor element and the acceleration sensor element that are generally packaged separately.
However, it is not necessarily easy to package both sensor elements integrally. Because the vibration-type angular velocity sensor detects an angular velocity about a detection axis of the vibration-type sensor element, there is a need to interpose a damper furnished with a vibration absorbing capability for suppressing an influence of disturbance, such as an external impact in packaging the vibration-type angular velocity sensor element to the exterior package. In contrast, because the acceleration sensor element detects acceleration with respect to a detection direction at a higher degree of accuracy, it has to be fixed rigidly to the exterior package for the acceleration added to the exterior package to be transmitted directly in packaging the acceleration sensor element to the exterior package.
Hence, in the case where the vibration-type angular velocity sensor element that needs a buffering structure, such as a damper, and the acceleration sensor element that needs a rigid fixing structure are incorporated together in a single package, the characteristics as the composite sensor would be deteriorated unless the mutually contradictory needs for both sensor elements were satisfied. A separate attaching structure for each has therefore been necessary, which consequently makes it difficult to reduce the composite sensor in size.